In living cells, RNA is normally associated with proteins to form various nucleoprotein complexes (RNPs). These RNAs are sometimes referred to as splicosomal RNA; ribosomal RNA (rRNA); RNA-associated enzymes, such as RNAses, RNA ligases and telomerase; messenger RNA (mRNA); transfer RNA (tRNA); heterogenous nuclear RNA (hnRNA); and small nuclear RNA (snRNA). The RNPs corresponding to such RNAs are commonly referred to with reference to similar or identical prefix designations, as in heterogenous nuclear protein complex or, simply, hnRNP. The protein component of the RNP is commonly referred to with reference to such prefix and the complex, as in heterogenous nuclear protein complex protein or, simply, hnRNP protein.
A significant portion of RNA-binding proteins mediate the post-transcriptional regulation of gene expression. Heterogenous nuclear RNAs (hnRNA) are the primary transcripts of protein coding genes. hnRNAs are processed in the nuclei of eukariotic cells and, at least a portion of such hnRNAs, become mRNAs. From the time hnRNAs emerge from the transcriptional complex, and throughout the time they are in the nucleus, they are associated with proteins termed as hnRNP proteins. Members of this family of proteins are required for multiple steps during mRNA metabolism, including pre-mRNA processing and mRNA localization, translation and stability. The majority of proteins associated with RNAs appear to be associated with hnRNAs and messenger RNAs (mRNAs) in hnRNP and mRNP complexes. However, there are numerous, less abundant proteins which are associated with other groups of RNAs (Dreyfuss et al., 1993).
Clearly, hnRNPs and other RNP complexes have great importance for cell function. And, the presence or absence of such RNP complexes, or abnormalities in such RNP complexes may have substantial implications in disease. By way of example, without limitation, the presence or absence or abnormalities in RNP complexes may be an indication of an inherited disease, cancer, prion disease, and age related disease.
Viral RNPs and their RNA and protein components define much of the disease processes associated with the virus pathogens (e.g.HIV, Dengue virus, etc.,). By way of example two viral enzymes, Tat and rev proteins, are essential in a life cycle of HIV and form an RNP. RNPs and their RNA and protein components, for both RNA and DNA viruses, have great value as diagnostic tools.
Bacterial and viral RNP complexes are attractive diagnostic targets. The RNP complexes of pathogens, and associated RNA molecules and protein components, may present much more numerous copies in a sample compared to genomic or ribosomal targets.
A need exists for analytical methods, compositions, kits and apparatus to identify and characterize new RNP complexes. Such analytical methods, compositions, kits and apparatus have utility in the diagnosis of various cancers, infectious and inherited diseases.